This study will investigate the effects of therapy with the novel HIV-1 protease inhibitor amprenavir on glucose and lipid metabolism and body composition. A frequent and serious complication of PI-based regimens for treatment of HIV include a spectrum of clinical disorders associated with peripheral fat wasting, increases in intra-abdominal (visceral) fat, increases in triglycerides and LDL cholesterol, decreases in HDL cholesterol, and insulin resistance. These complications, when they occur, are expected to increase the risk for cardiovascular morbidity and mortality. The primary endpoint measurements will be changes in insulin sensitivity by minimal model analysis, and serum lipid profiles.